Packed towers Hiflow rings

When molasses is fermented to produce a liquor containing ethanol, a C02-rich vapor containing a small amount of ethanol is evolved. The alcohol will be recovered by countercurrent absorption with water in a packed-bed tower. The gas will enter the tower at a rate of 180 kmol/h, at 303 K and 110 kPa. The molar composition of the gas is 98% C02 and 2% ethanol. The required recovery of the alcohol is 97%. Pure liquid water at 303 K will enter the tower at the rate of 151.5 kmol/h, which is 50% above the minimum rate required for the specified recovery (Seader and Henley, 1998). The tower will be packed with 50-mm metal Hiflow rings and will be designed for a maximum pressure drop of 300 Pa/m of packed height. 

A cooling tower, 2 m in diameter, packed with 75-mm ceramic Hiflow rings, is fed with water at 316 K at a rate of 25 kg/m2-s. The water is contacted with air, at 300 K and 101.3 kPa essentially dry, drawn upward coun-tercurrently to the water flow. Neglecting evaporation of the water and changes in the air temperature, estimate the volumetric rate of airflow, in m3/s, which would flood the tower. 

Consider the absorber of Examples 3.7 and 5.2. The adsorber will be packed with 50-mm metal Hiflow rings. Estimate the dimensions of the absorber and the power required to pump the gas and the liquid through the tower. Design for a gas-phase pressure drop of 300 Pa/m of packed height. 

To determine the tower diameter, consider the conditions at the bottom of the absorber where the maximum gas and liquid flow rates are found. Run the packed-tower design program of Appendix D using the data from Example 5.2 and packing parameters from Chapter 4. From Table 4.1 for 50-mm metal Hiflow rings ... 

Design a tower packed with 50-mm ceramic Hiflow rings for the carbon disulfide scrubber of Problem 5.11. Assume isothermal operation and use a liquid rate of 1.5 times the minimum and a gas-pressure drop not exceeding 175 Pa/m of packing. Calculate the tower diameter, packed height, and total gas-pressure drop. Assume that Ch for the packing is 1.0. 

Air at 300 K is used to dry a plastic sheet. The solvent wetting the plastic is acetone. At the end of the dryer, the air leaves containing 2.0 mol% acetone. The acetone is to be recovered by absorption with water in a packed tower. The gas composition is to be reduced to 0.05 mol% acetone. The absorption will be isothermal because of cooling coils inside the tower. For the conditions of the absorber, the equilibrium relationship is y. = 1.8 c.. The rich gas enters the tower at a rate of 0.252 kg/s, and pure water enters the top at the rate of 0.34 kg/s. The tower is packed with 25-mm metal Hiflow rings. Determine the dimensions of the tower. 

Repeat Example 6.16 for a tower packed with 50-mm metal Hiflow rings. Design for a 70% approach to flooding. 

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See also in sourсe #XX -- [ ]

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